I don't own a navy shirt and don't think I ever would but I do have a navy sweater and a sort of cotton pullover that are OK.

re: suits without ties, the only time I do this is when I am travelling and I don't want to pack the suit and I don't want to bother with a tie. Makes me feel vaguely sketchy, like a pick up artist, mobster, or professional con man.

Navy trousers are objectively wrong.
I don't own a navy shirt and don't think I ever would but I do have a navy sweater and a sort of cotton pullover that are OK.
re: suits without ties, the only time I do this is when I am travelling and I don't want to pack the suit and I don't want to bother with a tie. Makes me feel vaguely sketchy, like a pick up artist, mobster, or professional con man.

Why are they wrong? Because they are supposed to be part of a suit? Are there any other colors to avoid? I know to avoid black odd trousers.

Navy trousers are objectively wrong.
I don't own a navy shirt and don't think I ever would but I do have a navy sweater and a sort of cotton pullover that are OK.
re: suits without ties, the only time I do this is when I am travelling and I don't want to pack the suit and I don't want to bother with a tie. Makes me feel vaguely sketchy, like a pick up artist, mobster, or professional con man.

I agree - I feel somewhat incomplete wearing a suit without a tie.

If a more casual look is desirable, then an odd jacket without a tie is the solution (and I'm now leaning towards a button-down collar in that situation).

Also, I was considering buying some navy odd trousers, but would probably only wear them with a v-neck sweater, not an odd jacket.

re: suits without ties, the only time I do this is when I am travelling and I don't want to pack the suit and I don't want to bother with a tie. Makes me feel vaguely sketchy, like a pick up artist, mobster, or professional con man.

What you're feeling is a guilt. Your subconscious is saying. "I know better. I actually wrote the book. But here I am, in public, wearing a suit with no tie. Even worse, because I am so naturally fly, I know that these tired, poor, huddled masses are thinking. 'Wow! Look at that guy rocking the suit with no tie. He looks great! I'm going to do that too!'"

I don't know why navy odd trousers are wrong. I just know that they are.

Without a jacket they are not terrible but with a jacket, noooo.

A couple of years ago I had to be somewhere for a dinner and I also had a lunch in the same place. I wore my navy linen suit with a cream linen BD shirt. For the lunch and the rest of the afternoon I wore just the pants and the shirt with no coat or tie. Then for the dinner I put on the tie and coat. Could have been worse.

I don't know why navy odd trousers are wrong. I just know that they are.
Without a jacket they are not terrible but with a jacket, noooo.
A couple of years ago I had to be somewhere for a dinner and I also had a lunch in the same place. I wore my navy linen suit with a cream linen BD shirt. For the lunch and the rest of the afternoon I wore just the pants and the shirt with no coat or tie. Then for the dinner I put on the tie and coat. Could have been worse.

I don't know why navy odd trousers are wrong. I just know that they are.
Without a jacket they are not terrible but with a jacket, noooo.
A couple of years ago I had to be somewhere for a dinner and I also had a lunch in the same place. I wore my navy linen suit with a cream linen BD shirt. For the lunch and the rest of the afternoon I wore just the pants and the shirt with no coat or tie. Then for the dinner I put on the tie and coat. Could have been worse.

I have never worn them with an odd jacket, but I am guilty of having worn them without a jacket. I find this rule confusing. I get the "no black pants" thing because black suits are wrong also. But a navy suit is fine, so the no odd navy trouser thing is perplexing.

Side vents on all suit and sport coats; side vents or no vent on dinner jackets. Exception: an old, terminally faded, unconstructed patchwork madras jacket with a center vent and three open patch pockets; but I wear this more as a shirt over a colored tee or tank with washed out jeans and a bandana. (I fully understand if the previous sentence is deleted by the moderator, but it is true.)

All trousers double pleated, cuffed, and cut full to sit at the waist or slightly above; only forward pleats on suit trousers; forward or reverse pleats on odd trousers. Exceptions: Corduroys and chinos may be plain front, and chinos may be hemmed (stitched through) and rolled.

Side vents on all suit and sport coats; side vents or no vent on dinner jackets. Exception: an old, terminally faded, unconstructed patchwork madras jacket with a center vent and three open patch pockets; but I wear this more as a shirt over a colored tee or tank with washed out jeans and a bandana. (I fully understand if the previous sentence is deleted by the moderator, but it is true.)
All trousers double pleated, cuffed, and cut full to sit at the waist or slightly above; only forward pleats on suit trousers; forward or reverse pleats on odd trousers. Exceptions: Corduroys and chinos may be plain front, and chinos may be hemmed (stitched through) and rolled.
Overcoats and raincoats at least mid-calf length.
No bluchers with suits; oxfords, monks, dressy slipons all permitted.